Thermostat Falure and Overheating Raptor Engine

[PuraVida]

I was out surfing last weekend when my boat overheated. Ran for about 30 min before we lost power and shut the engine off. Blew the lid off the coolant reservoir. My raw water pump is working because I can see water running through my strainer. Had to get a tow in to prevent any damage. Dealer says it is the thermostat. Anyone else with a similar issue on the raptor 400? Roughly 270hrs.

Boat ran fine the weekend before but we never ran it hard because there was still ice on the lake.

[Stazi]

I was out surfing last weekend when my boat overheated. Ran for about 30 min before we lost power and shut the engine off. Blew the lid off the coolant reservoir. My raw water pump is working because I can see water running through my strainer. Had to get a tow in to prevent any damage. Dealer says it is the thermostat. Anyone else with a similar issue on the raptor 400? Roughly 270hrs.

Boat ran fine the weekend before but we never ran it hard because there was still ice on the lake.

Physically look at the raw water impeller and make sure it didn’t lose a cane and block the water line


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[mor3naz0]

Had the same problem and even though water seemed to be going through the strainer, the raw pump had failed.

I had it replaced and all good so far.


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[PuraVida]

Thank you for the responses. I emptied the strainer and it filled almost instantaneously. Will hopefully know more soon.


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[Casey B]

Did you find the issue? Mine overheated and went in limp mode yesterday. The raw water appears to be circulating fine but it continues to get hot. I checked the t star today and it appears to be working properly as well.

[Gene WB]

How did you end up fixing this problem. I am having the same issue.

Gene WB

[Tommy2slow]

Replaced my impeller and still have issues. Still overheating at low rpm. Cools fine above 2K. Replacing the impeller made no improvement. I’m leaning towards a faulty thermostat, anyone replaced this on a Raptor 400, and what is the difficulty rating for this repair?

[Holdmybeer]

It is as simple as you think. Pop the engine plastic cover off and the housing is right there in plain sight. 2 bolts and you are done.

There is a coolant drain somewhere also so you don't make a mess. However, don't you still have warranty...sound like a dealer problem. How backed up are they?

[Tommy2slow]

9 hour drive from the nearest dealership unfortunately. They will probably go good for parts warranty, but it’s going to be up to me to diagnose and repair for the time being.

[Holdmybeer]

If you get the boat to temp and grab the main 2" hose on the top of the engine headed to the heat exchanger canister it should be hard and have fluid in it. If the thermostat isn't working it will be super easy to squeeze and restrict flow further.

Have you had any other issue or work done? Could be an air bubble in the system.

[Tommy2slow]

Still haven’t solved my overheating issue. Replaced both the fresh water impeller and the thermostat. Not sure where to go now. After replacing the thermostat and topping up the coolant, I brought the engine up to temperature, it shot right past 160 and I shut it down at 180. At around 160 I expected to see the coolant reservoir level to drop, as I am suspecting that I still need to add more coolant, but it didn’t go down. Anybody have any ideas what might be happening?

[Zog]

Could your heat exchanger be plugged? We were having issues with a separate boat and found impeller pieces in the exchanger, resulting in the over temperature issues due to low water flow.

[Tommy2slow]

Not sure, the impeller that I removed was in perfect condition.

[Tommy2slow]

That large hose that comes ofF the thermostat housing is not hard or warm when the engine is up to temperature. I replaced the thermostat and no improvement.

[HFarr]

I had what Zog had happen in my old boat, too. But if your impeller was fine, maybe it sucked up something else, or possibly just corrosion or some other buildup that needs backflushing to get out.

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[Holdmybeer]

I can fix this for you.

I had the same issue and had to MacGyver it on the water.

From the top of the coolant reservior there is a small 1/4" hose.
Remove it at the reservoir and insert a small funnel and fill with coolant.
It will take forever but mine took 3/4 gallon of premix.
Once full, reconnect to reservoir.
Start the boat and watch Temps. It should burp air now.
Top off the reservior as needed.
Engine should stay cool on fake a lake.

FYI...this procedure is straight from the Indmar manual.

[Holdmybeer]

Tommy,
You ever get your overheating issue resolved?

[RUGER761]

Not sure, the impeller that I removed was in perfect condition.

Sorry kind of late on this one. Don't keep adding straight coolant to it, add distilled water. The coolant they use is very particular on the concentration, too high it will overheat in an instant, and of course too low it will freeze.

[Tommy2slow]

Thanks for the coolant advice, I added a 50/50 premix, but always good to remind the members. That coolant is super pricey btw! Could only find one supplier in my small town and it is almost $100/gallon (for premix!!!).

Haven’t resolved the issue yet. I tapped out, parked it for the season, and booked an appointment for next week with a local shop that does my winterizations.

I spoke with the service department for the Skiers dealer in BC, where I bought the boat, and they suspect the heater system. Apparently they are prone to vapour lock.

I will provide an update after I get it back from the dealer.


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[Tommy2slow]

The went to the dealer last week. After a few days of trouble shooting and working with the Indmar specialist at my dealer over the phone, I am no closer to resolving the issue. There is a possibility that pump for the heater is failing and causing enough restriction to inhibit coolant flow. Unfortunately, the dealer had already winterized the boat so we couldn’t bypass the pump and run it up to temp. Will have to try it again next spring.

[MJHSupra]

Bum deal on not being able to try more fixes. I'm surprised to hear about other owners (over the years) with heater issues or leaks from the heater fittings. Sounds like a weak spot for overheating issues.